Do you remember way back when you were reading Chapter 2? Those were good times, weren't they? After setting up the mobile in that exercise, you animated only the bars to rotate, but you left the rotation of the shapes for later. In this chapter, you'll pick up where you left off with the mobile from Chapter 2 and finish the animation using the hierarchies that were set up in that exercise.

If you haven't already done so from the previous Chapter 2 exercise, copy the Mobile project from the companion CD to your hard drive. Set your Max project folder by choosing File → Set Project Folder and selecting the Mobile project that you copied from the CD to your hard drive.

Animating the Shapes

With the Mobile_v05.max scene open (or your own file), scrub through the animation to become familiar with the scene. The intent here is to create a hierarchy in the mobile and animate the bars. Now you will add rotation to the shapes hanging from the bars. Figure 8.1 shows the mobile in mid-animation.

To add animation to the shapes under the bars, follow these steps:

Figure 8.1. The mobile is back!

Figure 8.2. Rotate the triangle 360 degrees or more in Z.

Figure 8.3. The square is rotated, and its child bar goes along for the ride.

Now scrub your animation and check the results. In theory, all the bars should rotate and so should the shapes hanging on the bars. When you scrub, however, the mobile will seem to have lost its mind. The shapes will rotate completely off axis, as if you have set rotation keyframes on the X- and Y-axes as well as the intended Z-axis. The same will occur with the lower bar. It will go off its axis and rotate in an unpredictable manner. This behavior is explained in the next section, with easy solutions to fix the issue.

Figure 8.4. Rotate the star in Z.

Making a Mistake

Why would we purposely show you an incorrect workflow? Because learning from missteps is as important to learning CG as learning the correct steps. Being able to troubleshoot is essential to becoming good in CG, and the more trouble you get yourself into, the better you will become at digging your way out.

This example of strangely rotating hierarchies is an isolated issue that is called gimbal lock in many CG circles. Different CG packages have different ways of interpreting exactly how an object rotates when it is rotating along more than one axis. Imagine three cars all staring each other down at a three-way intersection—with the traffic light out. Who goes first in this situation is important to the flow of traffic at the intersection. When a 3D package calculates rotations, it needs to know which axis to rotate first before tending to the rotation of the other axes. In 3ds Max, the animation controller is the traffic light directing the animation. With gimbal lock, you have an incorrect interpretation of the rotations, so the resulting animation seems off axis.

In this exercise, the multiple rotations inherited by the children shapes and bars from their parents caused havoc with their own rotations, so the axes became confused and everything looks just plain wrong. The easiest way to fix this issue is to reassign the animation controllers in charge of the rotations for those objects to one that will not lock up.

Making a Mistake

Why would we purposely show you an incorrect workflow? Because learning from missteps is as important to learning CG as learning the correct steps. Being able to troubleshoot is essential to becoming good in CG, and the more trouble you get yourself into, the better you will become at digging your way out.

This example of strangely rotating hierarchies is an isolated issue that is called gimbal lock in many CG circles. Different CG packages have different ways of interpreting exactly how an object rotates when it is rotating along more than one axis. Imagine three cars all staring each other down at a three-way intersection—with the traffic light out. Who goes first in this situation is important to the flow of traffic at the intersection. When a 3D package calculates rotations, it needs to know which axis to rotate first before tending to the rotation of the other axes. In 3ds Max, the animation controller is the traffic light directing the animation. With gimbal lock, you have an incorrect interpretation of the rotations, so the resulting animation seems off axis.

In this exercise, the multiple rotations inherited by the children shapes and bars from their parents caused havoc with their own rotations, so the axes became confused and everything looks just plain wrong. The easiest way to fix this issue is to reassign the animation controllers in charge of the rotations for those objects to one that will not lock up.

Figure 8.5. The Assign Controller rollout in the Motion panel

Animation Controllers

By default, 3ds Max assigns a Euler XYZ controller to the rotations of objects. This is the best controller to use in the majority of circumstances. In this example, however, it doesn't quite work. To assign a different controller, follow along here:

If Euler XYZ caused such a ruckus, why isn't TCB Rotation the default for rotating objects? For one thing, the editing options you have with a Euler XYZ controller are head and shoulders above what you get with TCB Rotation. With the Euler XYZ, 3ds Max splits the XYZ rotation animation into three separate tracks to give individual control over each axis. This is ideal.

In addition, the TCB Rotation has taken the several hundred degrees of rotation you have animated, and cut it down to within 180 degrees of rotation at most. The square, triangle, and star don't seem to be rotating the several hundred degrees you intended.

Figure 8.6. Choosing TCB Rotation limits your options and the rotation.

Figure 8.7. You've fixed the rotation of the square and its children.

Figure 8.8. The mobile seems to rotate properly, but does it really?

Editing the TCB Rotation Keyframes

To fix the problem that the objects do not rotate the several hundred degrees you want, you will have to manually edit the controller to allow a greater degree of rotation:

Any parameter that is animated has a controller. A controller essentially deals with all the animation functions in the scene for 3ds Max, such as storing keyframe values. Interpolating in-betweens is handled by the controllers. By default, the Position XYZ controller is assigned to an animation on an object's position and a Euler XYZ is assigned to its rotation. These controllers are the most useful as they split the X, Y, and Z into separate tracks to give individual control over each axis. You will have the opportunity to work with and edit individual tracks later in this chapter.

Figure 8.9. Edit your controller in the Key Info rollout.

Figure 8.10. Adding more rotation to the square in the Key Info rollout

Another way to circumvent this particular issue of rotation confusion is by using helper objects in 3ds Max called dummy objects. Changing the controller for an object is not always the best solution—particularly if the range of movement will be changed. You saw this problem when you changed to TCB Rotation before you had to fix it in Key Info to add more rotation. Using dummy objects, you can insert a helper in the hierarchy that will negate the gimbal lock issue and make it very clear to 3ds Max how the rotations should proceed. As a matter of fact, it's common for animators to make copious use of dummies as controllers for their animation rigs. A rig is essentially any setup in the scene that helps you animate objects in the scene.

Dummies (called null nodes in other CG applications such as Maya) are very useful nonrendering objects that can be used in several ways. In this case, they serve as placeholders and are used directly in the hierarchy to straighten out the rotation confusion. They serve as parents to the mobile shapes that may come down with rotation confusion or gimbal lock.

Placing Dummies in the Mobile

To create dummy objects for the animation hierarchy, follow these steps:

Play the animation. As you can see, the funky rotation is gone and now you have a perfectly normal rotation. The bar's rotation moves the dummy below it, and the dummy pulls the circle. Because the bar is not directly pulling the circle, the circle is free to rotate without rotation confusion.

Once you feel confident with how this exercise works, you should have a pretty solid idea of how hierarchies work in animation. Feel free to go through this entire exercise another time before moving on.

Figure 8.13. Success! The circle is now rotating properly.

Editing Dummies

Each dummy gets its orientation from the viewport in which you create it. When you place one of the mobile's dummies, you don't need to have it aligned perfectly with the shape for which the dummy is being used. However, it is a good idea to match things up as best as you can to keep track of which dummy goes with which shape.

Let's say you created a dummy and it is nowhere near its shaper. The Align tool can move the dummy so it is centered on the shape. To see how the Align tool works, follow along with these steps:

Figure 8.14. Create a dummy.

Although it may seem like more work, using dummies is a great workflow for animation. It keeps the scene's animation neater and better defined. As you gain more experience, you will begin to learn when you should use dummies in your hierarchy to make the animation workflow smooth.

Figure 8.15. The Align Selection dialog window

A classic exercise for all animators is creating a bouncing ball. As a matter of fact, you will find bouncing ball tutorials almost everywhere you look. Although you will see it as a straightforward exercise, there is so much you can do with a bouncing ball to show character, that the possibilities are almost limitless. Animating a bouncing ball is a good exercise in physics, as well as cartoon movement. You'll first create a rubber ball, and then you'll add cartoonish movement to accentuate some principles of the animation techniques discussed in Chapter 1, "Basic Concepts." Aspiring animators can come use this exercise for years and always find something new to learn about bouncing a ball.

In preparation, copy the Bouncing Ball project from the CD to your hard drive. Set your current project by choosing File → Set Project Folder and selecting the Bouncing Ball project that you copied from the CD to your hard drive.

Figure 8.16. Aligned to center

Animating the Ball

Your first step is to keyframe the positions of the ball. As introduced in Chapter 1, keyframing is the process—borrowed from traditional animation—of setting positions and values at particular frames of the animation. The computer interpolates between these keyframes to fill in the other frames to complete a smooth animation.

You'll start with the gross animation, or the overall movements. This is also widely known as blocking. First, move the ball up and down to begin its choreography.

Follow these steps to animate the ball:

Figure 8.17. At frame 10, move the ball to meet the ground plane.

This has created two keyframes, one at frame 0 for the original position the ball was in, and one at frame 10 for the new position to which you just moved the ball.

Copying Keyframes

Now you want to move the ball up to the same position in the air as it was at frame 0. Instead of trying to estimate where that was, you can just copy the keyframe at frame 0 to frame 20.

You can see the keyframes you created in the timeline. They are red tick marks in the timeline. Red keys represent Position keyframes, green keys represent Rotation, and Blue keys represent Scale. When a keyframe in the timeline is selected, it turns white. In Figure 8.18, the keyframe at frame 0 is selected and is white.

Figure 8.18. Selected keys in the timeline are white.

Right now the ball is going down and up.

To continue the animation for the length of the timeline, you could continue to copy and paste keyframes—but that would be very time-consuming, and you still need to do your other homework and clean your room. A better way is to loop or cycle through the keyframes you already have. An animation cycle is a segment of animation that is repeatable in a loop. The end state of the animation matches up to the beginning state, so there is no hiccup at the loop point.

In 3ds Max, cycling animation is known as Parameter Curve Out-of-Range Types. This is a fancy way to create loops and cycles with your animations and specify how your object will behave outside the range of the keys you have created. This will bring us to the Track View, which is an animator's best friend. You can go through the Track View's UI in the "Track View" section later in this chapter at any time, or you can hang tight and see how you work with Track Editor first using the Bouncing Ball exercise. You will learn theunderlying concepts of the Track Editor throughout this exercise as well as its basic UI. Feel free to reference the "Track View" section as you continue.

The Track View is a function of two animation editors, the Curve Editor and the Dope Sheet Editor. The Curve Editor allows you to work with animation depicted as curves on a graph that sets the value of a parameter against time. The Dope Sheet Editor displays keyframes over time on a horizontal graph, without any curves. This graphical display simplifies the process of adjusting animation timing because you can see all the keys at once in a spreadsheet-like format. The Dope Sheet is similar to the traditional animation exposure sheets or X Sheets.

You will use the Track View-Curve Editor (or just Curve Editor for short) to loop your animation in the following riveting steps:

Reading Animation Curves

As you can see, the Track View-Curve Editor (from here on called just the Curve Editor) gives you control over the animation in a graph setting. Curves allow you to visualize the interpolation of the motion. Understanding what animation curves do in the Curve Editor is critical to getting your animation to look right. Once you are used to reading animation curves, you can judge an object's direction, speed, acceleration, and timing at a mere glance.

The Curve Editor's graph is a representation of an object's parameter, such as position (values shown vertically) over time (time shown horizontally). Every place on the curve represents where the object is; a keyframe does not need to be on the curve. So, the shape of the curve makes a big difference in the motion of the object.

Here is a quick primer on how to read a curve in the Curve Editor.

In Figure 8.22, an object's Z Position parameter is being animated. At the beginning, the curve quickly begins to move positively (that is, to the right) in the Z-axis. The object shoots up and comes to an ease-out, where it decelerates to a stop, reaching its top height. The ease-out stop is signified by the curving beginning to flatten out at around frame 70.

Figure 8.22. The object quickly accelerates to an ease-out stop.

PARAMETER CURVE OUT-OF-RANGE TYPES

There are several ways to interpret the curves of an animation when they are out-of-range, meaning when they extend before your first keyframe and beyond your last keyframe. The Parameter Curve Out-of-Range Types is opened through the Curve Editor with this toolbar button (

Constant Used when you do not want any animation out-of-range. This curve type will hold the value of the end and or beginning key of the range for all frames. Constant is the default out-of-range type.

Cycle Used when you need the animation to loop or cycle by repeating the same animation that is within the range. If the first keyframe does not line up with the last keyframe of the curve range, there will be an abrupt "jump" from the last key to the first with every cycle. If the start and end values do not need to match, and that hiccup in the cycle is desired, use Cycle.

Loop Used when you need the animation to loop or cycle smoothly despite any differences in the start and end keyframe values. Loop repeats the same animation in the curve range, but it also interpolates between the last and first keyframes in the range to create a smooth loop in the cycle. Loop's ability to create a smooth loop can only go so far before it acts like a Cycle (e.g., when the key values at the start and end are too disparate).

Ping Pong Used when you want your animation to oscillate back and forth. Ping Pong repeats the same animation in the range, but it plays it front to back and then back to front, and so forth, to alternate the playback, as shown here.

Linear Used when you need your animation to continue at the same velocity as its beginning or end. The animation curve is projected out from the range in a straight line, picking up the trajectory from the shape of the start or end of the curve, as shown here.

Relative Repeat Used when you need your animation to repeat as in a cycle and to continue building on itself as it cycles. Each repetition is offset by the value at the end of the range, as shown here.

You can select any one of these types for either the before or after by clicking one of the smaller boxes below the thumbnails. You can set both the before and after out-of-range type by clicking the thumbnail of the type itself.

You can select any one of these types for either the before or after by clicking one of the smaller boxes below the thumbnails. You can set both the before and after out-of-range type by clicking the thumbnail of the type itself.

Figure 8.23. The object eases in to acceleration and suddenly stops at its fastest velocity.

In Figure 8.24, the object eases in and travels to an ease-out where it decelerates starting at around frame 69 to where it slowly stops at frame 75.

Figure 8.24. Ease-in and ease-out

Finally, in Link , the object jumps from its Z Position in frame 24, to its new position in frame 25.

Figure 8.25. Step interpolation makes the object "jump" suddenly from one value to the next.

Figure 8.26 shows the Track View-Curve Editor, with notes on its major aspects called out for your information. See the "Track View" section later in this chapter for a more thorough explanation of the UI and toolset for the Track View.

Figure 8.26. The Curve Editor

Refining the Animation

Now that you've played back the gross animation of the bounce, how does it look? Not like a ball bouncing, really, but the framework is getting there. Notice how the speed of the ball is consistent. If this were a real ball, it would be dealing with gravity; the ball would speed up as it gets closer to the ground and there would be "hang time" when the ball is in the air on its way up as gravity takes over to pull it back down.

This means you have to edit the movement that happens between the keyframes. This is done by adjusting how the keyframes shape the curve itself using tangents. When you select a keyframe, a handle will appear in the UI, as shown in grayscale in Figure 8.26 and shown up close here.

This handle adjusts the tangency of the keyframe to change the curvature of the animation curve, which in turn changes the animation. There are different types of tangents, depending on how you want to edit the motion. By default the Smooth tangent is applied to all new keyframes. This is not what you want for the ball, although it is a perfect default tangent type to have.

Editing Animation Curves

Let's edit some tangencies to better suit your animation. The intent is to speed up the curve as it hits the floor and slow it down as it crests its apex. Instead of opening the Curve Editor through the menu bar, this time you are going to use the shortcut. At the bottom of the interface, click the Mini Curve Editor button shown here.

This Mini Curve Editor is almost exactly the same as the one you launch through the main menu bar. A few tools are not included in the Mini Curve Editor toolbar, but you can find them in the menu bar of the Mini Curve Editor. Figure 8.27 shows the Mini Curve Editor open in the 3ds Max UI.

Figure 8.27. The Mini Curve Editor

To edit the curves, follow these steps:

Although the animation has improved, the ball has a distinct lack of weight. It still seems too simple and without any character. In situations such as this, an animator can go wild and try several different things as he or she sees fit. This is where creativity helps hone your animation skills, whether you are new to animation or have been doing it for fifty years.

Animation shows change over time. Good animation conveys the intent, the motivation for that change between the frames.

Squash and Stretch

The concept of squash and stretch has been an animation staple for as long as there has been animation. It is a way to convey the weight of an object by deforming it to react (usually in an exaggerated way) to gravity, impact, and motion.

You can give the ball a lot of flare by adding squash and stretch to give your object some personality. Follow along with these steps:

Setting the Timing

Well, you squashed and stretched the ball, but it still doesn't look right. That is because the ball should not begin to squash too long before it hits the ground. It needs to return to 100 percent scale and stay there for a few frames. Immediately before the ball hits the ground, it can squash into the ground plane to heighten the sense of impact. The following steps are easier to perform in the regular Curve Editor rather than in the Mini Curve Editor. Close the Mini Curve Editor by clicking the Close button.

Open the Curve Editor to fix the timing, and follow these steps as if they were law:

Once you play back the animation, the ball will begin to look a lot more like a nice cartoonish one, with a little character. Experiment with changing some of the scale amounts to have the ball squish a little more or less, or stretch it more or less to see how that affects the animation. See if it adds a different personality to the ball. If you can master a bouncing ball and evoke all sorts of emotion with your audience, you will be a great animator indeed.

Moving the Ball Forward

Now that you have worked out the bounce, it's time to add movement to the ball so that it moves across the screen as it bounces. Layering animation in this fashion, where you settle on one movement before moving on to another, is common. That's not to say you won't need to go back and forth and make adjustments through the whole process, but it's generally nicer to work out one layer of the animation before adding another. The following steps will show you how:

Adding a Roll

You need to add some rotation, but there are several problems with this. One, you moved the pivot point to the bottom of the ball in the very first step of the exercise. You did that so the squashing would work correctly, that is at the point of contact with the ground. If you were to rotate the ball with the pivot at the bottom, it would look like Figure 8.39.

Figure 8.39. The ball will not rotate properly because the pivot is at the bottom.

Using the XForm Modifier

You need a pivot point at the center of the ball, but you can't just move the existing pivot from the bottom to the middle—it would throw off all the squash and stretch animation.Unfortunately, an object can have only one pivot point. To solve the issue, you are going to use a modifier called XForm. This modifier has many uses. You're going to use it to add another pivot to the ball in the following steps:

Now to be clear, this isn't a pivot point. This is the center point on the XForm modifier. If you go to the Modifier Stack and click on the Sphere, the pivot point will still be at the bottom, as shown here.

Now, the XForm modifier allows the ball to rotate, without Squash and Stretch getting in the way. By separating the rotation animation for the ball's roll into the modifier, the animation on the sphere object is preserved.

Animating the XForm Modifier

To add the ball's roll to the XForm modifier, follow along with these illuminating and incredibly insightful steps:

The ball should be a rubbery cartoon ball at this point in the animation. Just for practice, let's say you need to go back and edit the keyframes because you rotated in the wrong direction and the ball's rotation is going backward. Fixing this issue requires you to go back into the Curve Editor as follows:

Open the Curve Editor (mini or regular). Scroll down in the Controller window until you see the Ball tracks. Below the Ball's Transform track is a new track called Modified Object. Expand the track by clicking on the plus sign in the circle next to the name. Go to the gizmo and select Y Rotation Track (Figure 8.40).

You will see the Function curve in the Edit Key work area. You want the keyframe at frame 0 to have the value 0 and the keyframe at frame 100 to be 360 degrees. Select both keyframes and change the Tangent to Linear, as shown in Figure 8.41.

Close the Curve Editor and play the animation. Play the Bounce Ball.mov QuickTime movie file located in the RenderOutput folder of the Bouncing Ball project on your hard drive (or on the CD) to see a render of the animation. You can also load the Animation_ Ball_02.max scene file from the BouncingBall project folder on your hard drive (or on the CD) to check your work.

Figure 8.40. The XForm's gizmo selected in the Curve Editor window

Bouncing Ball Summary

Working with the bouncing ball gave you quite a bit of experience with the 3ds Max's animation toolset. There are several ways to animate a bouncing ball in 3ds Max. It is definitely a good idea to try this exercise a few times at first, and then to come back to it later—after you have learned other 3ds Max techniques.

Track View

As you have already seen, the Track View-Curve Editor is a powerful tool for creating and editing your animation scenes. In this section, the user interface for the Track View is laid out and explained as a brief reference for you. Figure 8.42 shows the Track View-Curve Editor.

Figure 8.41. Setting the rotation of the ball

Figure 8.42. The Track View-Curve Editor

The Curve Editor window can be a bit daunting at first. Now that you've had some experience with it in this chapter, it should seem pretty straightforward. The left side of the window (called the Controller window) displays the objects in the scene in an outline format. These objects have subheadings called tracks under them when they are animated. Each track will define animation on one axis of movement or rotation or scale, or one parameter that is keyframed. When you click on a track, its animation information will display in the graph area on the right. In the Curve Editor, you can access the curves and keyframes to edit the animation. In the Dope Sheet version of the Track View, you can access keys in a different manner, as discussed in the next chapter.

You can switch between the Curve Editor and the Dope Sheet by selecting the desired window in the Modes menu in the main menu bar. Most of the tools discussed here are also accessible through the menu bar and the toolbar. The toolbar is divided into function sets.

Key Tools Toolbar

The following table lists the tools used in editing keys in the Curve Editor window. You used a few of these tools in the Bouncing Ball animation.

I C O N	NAME	F U N C T I O N
	Filter	Filters the display in the Curve Editor to make viewing complicated scenes easier.
	Move Keys	Lets you select a keyframe and move it freely in the graph.
	Move Keys Horizontal	Lets you select a keyframe and move it horizontally, to change its timing only.
	Move Keys Vertical	Lets you select a keyframe and move it vertically, to change its value only.
	Slide Keys	Lets you select keyframes and move the group and slide the adjacent keys away as you move the group.
	Scale Keys	Lets you select keys and scale them to expand or compress the amount of time between them.
	Scale Values	Lets you select keys and increase or decrease the values of the keys proportionally without moving them in time.
	Add Keys	Add keys to an existing animation by clicking a curve.
	Draw Curves	Draw new curves, or revise existing curves, by drawing directly on the animation curve graph.
	Reduce Keys	Reduce keys when you have more keys than necessary on a curve.

Key Tangency Toolbar

As you saw with the bouncing ball, changing the tangency on a few keys can dramatically alter the look of your animation. By default, new keys are set to Auto Tangents, which generally keep the curve smooth. 3ds Max sets an appropriate tangency automatically; however, you can easily change the tangency by manually moving the handles on the keyframes. Once you select an Auto Tangent's handle, 3ds Max will automatically shift the handle to a custom handle, allowing you to move it. The following table lists the icons for the tangency tools.

I C O N	NAME	F U N C T I O N
	Set Tangents to Auto	This rollout icon boasts three tools for controlling Auto tangents. The top icon sets both handles to Auto, the middle sets the In tangent, and the bottom icon sets the Out tangent to Auto.
	Set Tangents to Custom	Custom tangents allow you to move the handles to form your own curvature. If you hold the Shift key as you drag a tangent handle, it will break continuity with the other handle, allowing you to have a different In tangency than Out tangency.
	Set Tangents to Fast	Sets the tangent to accelerate in or out of a keyframe quickly, or both.
	Set Tangents to Slow	Sets the tangent to go slowly into or out of the keyframe, or both.
	Set Tangents to Step	Sets the tangent to "jump" from one value to the next in a single frame. The animation will be frozen until the next keyframe when it will jerk to that position or value.
	Set Tangents to Linear	Sets the tangency to a straight linear progression into or out of the keyframe, or both.
	Set Tangents to Smooth	Attempts to keep the curve smooth across all values to achieve a more realistic motion in many cases.

Curves Toolbar

The Curves tools act on the animation curves themselves, allowing you to easily make changes to an animated track. You will run into some of these tools as you become more experienced with Max. Don't worry about memorizing all these functions.

I C O N	NAME	F U N C T I O N
	Lock Selection	Locks the current selection so you don't accidentally select something else.
	Snap Frames	Snaps keys to frames when you move them. When off, you can move keys to sub-frames (i.e., in-between frames).
	Parameter Out-of-Range Curves	Allows you to set the behavior of your animation before and beyond the keyframed range.
	Show Keyable Icons	Toggles an icon to tell you whether a track is keyable or not. Red is keyable; black is not.
	Show Tangents	Toggles the display of tangent handles on individual curves.
	Show All Tangents	Toggles the display of tangent handles on all curves in the graph.
	Lock Tangents	Locks a selection of tangent handles so you can adjust them all at once. When off, however, you only have access to one tangent handle at a time.

Biped Toolbar

These new Curve Editor Biped tools make the process of using the Curve Editor for biped animation much more streamlined than before. Biped tools will be covered in the next chapter. The following table lists the icons and their names for your reference. The Biped toolbar is visible only if you have a biped in your scene.

I C O N	NAME
	Show Biped Position Curves
	Show Biped Rotation Curves
	Show Biped X Curves
	Show Biped Y Curves
	Show Biped Z Curves

Navigation Toolbar

These tools are for Track View navigation. Tools such as Pan, Zoom, and Zoom Region work the same as in the Viewport Navigation tools. Some of the tools are designed specifically for the Track View. A few often-used icons are listed in the following table:

I C O N	NAME	F U N C T I O N
	Pan	Use this tool to drag the key window. You can also use the middle mouse button.
	Zoom Horizontal Extents	Adjusts the display so that the entire active time segment is shown.
	Zoom Value Extents	Adjusts the display so that the full heights of the curves are visible.
	Zoom	Zooms both time and value proportionally together. This is a rollout with two other Zoom options nested.
	Zoom Region	Lets you drag a region to scale the display to fit.

This exercise will give you more experience animating in 3ds Max. In it, you'll animate a knife being thrown at a target. You will edit more in the Curve Editor and be introduced to the concept of anticipation in animation, as well as momentum and secondary movement.

Blocking Out the Animation

To begin this exercise, open the Animation_Knife_00.max file in the Knife project and follow along here:

That's it for the gross animation or blocking of the shot. Did you have fun?

Trajectories

When it comes to animation, it is very helpful to be able to see the path your object is taking over time. These paths are known as trajectories in Max. The easiest way to see the trajectories is to select the knife object, go to the Motion panel, and click Trajectories, as shown in Figure 8.49. Your viewports will display a red curve to show you the path of the knife's motion as it arcs toward the target, as shown in Figure 8.50.

The trajectory will remain displayed until a moving object is selected. The large hollow square points on the trajectory curve represent the keyframes set on the knife so far. Let's adjust the height of the arc using the trajectory curve. Turn on the Sub-Object button at the top of the Motion panel (Figure 8.51).

Figure 8.49. Turning on trajectories for the knife

Figure 8.50. The curve shows the trajectory for the knife's motion.

Keys are your only sub-object choice in the pull-down menu to the right of the button. Select the middle keyframe and move it up or down to suit your tastes, as shown in Figure 8.52. Once you settle on a nice arc for the path of the knife, turn off the Trajectories button.

As you can imagine, the Trajectories panel can be useful in many situations. It not only gives you a view of your object's path, but it also allows you to edit that path easily and in a visual context, which can be so important.

Figure 8.51. Choose the subobject level.

Adding Rotation

The next step is to add a bit of rotation to the knife. As an animator, you need to research and gather as much information about your subject matter as you can. Throwing knives is usually a bad idea, but you can throw something else—ideally something that is shaped and weighted like a knife—at a target (the inanimate kind) to see how to animate your knife. Almost invariably, you'll find that the object will have to rotate once or twice before it hits its target. To add rotation to your CG knife, follow these steps:

With just a little bit of fast rotation as the knife leaves frame 10, you give the animation more spice. A little change in the curve can make a big difference in an animation—every little bit counts. The knife should now have a slightly weightier look than before when it rotated with an ease-in and ease-out.

Adding Anticipation

Instead of making the knife just fly through the air toward the target, you should animate it to move back first to create anticipation, as if an invisible hand holding the knife pulled back just before throwing it to get more strength in the throw. This anticipation, although it's a small detail, can add a level of nuance to the animation that enhances the total effect. Follow these steps:

Remember, the smallest tweaks in the Curve Editor can have a huge positive or negative impact on your animation.

Figure 8.59. To create a believable anticipation for the knife throw, set your curve to resemble this one.

Follow-Through

The knife needs more weight. A great way to show that in animation is by adding followthrough. This is part of the animation concept of secondary movement that was mentioned in Chapter 1. The follow-through for the knife would be having the knife sink into the target a little bit and push back the target as it transfers momentum to the target. For more on momentum, see the sidebar later in this chapter.

Knife Follow-Through

To add follow-through to your animation, follow these steps:

Figure 8.61. Set −655 at frame 35.

Be careful about how much the knife sinks into the target. Although it is important to show the weight of the knife, it is also important to show the weight of the target; you do not want the target to look too soft. Make sure your keys at frame 35 for the X Position and X Rotation are not too much.

Transferring Momentum to the Target

To make the momentum work even better for the Knife animation, you will have to push back the target as the knife hits it. The trouble is, if you animate the target moving back, the knife will float in the air. You have to animate the knife with the target. However, animating them separately in the hopes they will match up will frustrate you and will more than likely look bad.

If you think that hierarchy has to be involved here, you are absolutely right. Basically, the knife will have to be linked to the target so that when the target is animated, the knife will follow precisely, because it is stuck in the target.

This won't mess up the animation of the knife. Because the knife will be the child in the hierarchy and can have its own animation separate from the target, you can link it after you are finished with the knife animation. Just follow these steps:

Done! Play back your animation. Experiment and change some of the final timings of the target's reaction to the impact, as well as some of the values, to see how small changes can make big differences in how the weights of the knife and target look to the viewer.

Figure 8.64. The target animation curve

In this, the first of two chapters on animation in this book, you learned the basics of creating and editing animation. You learned how to fix hierarchy problems in animation and how to use dummy objects to help you animate properly. You bounced a ball to learn timing issues and how to edit animation curves through the Curve Editor. You then learned the ins and outs of the Track Editor-Curve Editor before moving on to a thrown knife to learn about trajectories and the concepts behind using secondary movement to help give your animation weight.

Animation can be a lot of fun, but it is also tedious and sometimes aggravating. A lot of time, patience, and practice are required to become good at animation. It all boils down to how the animation makes you think. Is there enough weight to the subjects in the animation? Do the movements make sense? How does nuance enhance the animation? These are all questions you will begin to discover for yourself. This chapter merely introduced you to how to make things move in 3ds Max. It gave you some of the basics of animation techniques to help you develop your eye for motion. Don't stop here. Go back into the chapter and redo some of the exercises. Try different variations on the same themes. Keep working.